1. Field of the Invention
The present invention relates to optical systems for reading one or two-dimensional bar code symbols, and more particularly, to a bar code label printer having an integrated optical scanner module that permits a desired bar code label to be scanned, identified and reproduced.
2. Description of Related Art
In the automated identification and data capture industry, it is known to use bar code symbology to encode alphanumeric information. A conventional bar code symbol represents a one-dimensional form of symbology, and comprises a pattern of vertical bars of various widths separated by spaces of various widths. Since the conventional one-dimensional symbols require a relatively large amount of space to convey a correspondingly small amount of data, two-dimensional bar code symbols have been developed. A two-dimensional symbol may comprise a matrix that occupies a uniform amount of space having a generally rectangular or square shape. Round or square dots disposed in particular rows and columns of the matrix correspond to the characters being conveyed. As a result, a two-dimensional matrix symbol can compress significantly more data into a given volume of space than a conventional one-dimensional bar code symbol. Examples of commercially available two-dimensional symbologies include Code One, Data Matrix and PDF417.
To read a bar code symbol, the bar code reader typically uses a light source, such as a laser, that is drawn across the bar code field. Since the black and white elements of the bar code symbol have different light reflecting characteristics, the reader can convert the symbol into an electrical signal by analyzing the light that has reflected from the symbol. The electrical signal can then be decoded to provide an alphanumeric representation of the symbol. Alternatively, the reader may include charge-coupled device (CCD) elements to form a memory-mapped image of a region of interest which includes an embedded one or two dimensional bar code symbol. The memory-mapped image may then be processed to locate, orient and decode the information that corresponds to the embedded bar code symbol.
In order for the bar code reader to accurately read the bar code symbol, it is essential that the symbol be printed in a high quality manner, without any streaking, blurring or improper registration to a label on which the symbol is printed. Since the bar code symbols are often printed on adhesive labels, it is essential that the adhesive backing layer of the labels not be damaged by heat generated during the printing process. In view of these demanding printing requirements, bar code symbols are often printed using direct thermal or thermal transfer printing techniques, referred to collectively herein as thermal printing.
The medical industry has made extensive use of automatic identification systems to improve the efficiency of medical care. Bar code labels are often used for tracking patient medical records in which a unique bar code symbol is used to identify each particular patient. To ensure correlation with the patient, all items pertaining to the patient, such as x-rays, test reports and specimens, may be affixed with a label bearing the patient's unique bar code symbol. It may be appreciated that this type of patient identification system increases the accuracy of medical care by preventing the patient's records from becoming mixed up, and enabling misplaced record items to be correlated to a particular patient's record.
Notwithstanding these advantages of automatic identification systems to the medical industry, they also present logistical problems to the medical support staff that must ensure that there is a ready supply of pre-printed labels having each patient's unique bar code symbol. For example, it often becomes necessary to reproduce (i.e., "clone") a bar code label that had been printed previously. Rather than using pre-printed labels, a medical office or facility may be provided with a thermal printer for printing additional bar code labels on demand. The thermal printer may be coupled to a computer, or a local area network (LAN) tying together several computers, that is accessible by an administrative member of the medical support staff to retrieve a patient's data record and instruct the printer to print a desired number of the labels. This can be a cumbersome and time consuming task that takes the medical support staff member away from the primary responsibility of providing medical care to the patients. Moreover, additional training is often required to teach the medical support staff to operate the computer system, which adds to the costs associated with operating such a system.
Thus, it would be very desirable to provide a fast and convenient system for operators of an automatic identification and data capture system to reproduce bar code labels on demand. It would be further desirable to provide a simple system that eliminates the need for cumbersome and time consuming interaction with computer systems to locate and retrieve stored data records, or extensive training to operate.